GRAPPA-based simultaneous multislice reconstruction using concentric ring k-space

PURPOSE: Simultaneous multislice (SMS) imaging is an effective method for accelerating fMRI and DTI because it can provide acceleration even with the single-shot acquisitions commonly used in these applications. Previous SMS methods have either focused on Cartesian trajectories [1], or used time-consuming iterative SENSE-like reconstructions on spiral data [2]. We propose a non-iterative GRAPPA-based reconstruction method on non-Cartesian data. A concentric ring trajectory is used to facilitate the sampling regularity needed for accurate kernel weights, and a blipped zgradient is used to help slice separation [1,2]. The concentric ring trajectory achieves most of the same benefits as conventional spirals in fMRI, with only a small increase in readout length. The methods and results here use 3 simultaneous slices with an 8-channel head coil.